Within digital systems, analog data signals may be transmitted from a transmitter to a receiver through a channel established therebetween. The communications channel (hereafter, “channel”) may comprise any suitable medium that links the transmitter to the receiver, which can include a wired or wireless channel. Depending on the particular application, the channel may be quite lossy, especially for digital systems involving high data transmission speeds, such as over a Universal Serial Bus (USB) channel. Analog data signal losses due to various channel transmission effects, such as interference, attenuation, and delay, may have detrimental effects on a transmitted analog data signal by the time the transmitted analog data signal reaches the receiver. The channel transmission effects can distort the transmitted analog data signal (e.g., cause amplitude or phase distortion), which in turn can result in ISI in the transmitted analog data signal received by the receiver. By ISI, a pulse or other symbol in a transmitted analog data signal, representing the logic state of one data bit at a cursor, may be effectively distorted. ISI generally comprises a pre-cursor component (hereafter, “pre-cursor ISI”) that distorts a transmitted analog data signal with respect to one or more data bits preceding a bit corresponding to a cursor of the transmitted analog data signal, and a post-cursor component (hereafter, “post-cursor ISI”) that distorts the transmitted analog data signal with respect to one or more data bits succeeding a bit corresponding to a cursor of the transmitted analog data signal.
Traditionally, a receiver can implement decision feedback equalization (DFE) to correct for post-cursor ISI in an analog data signal received at the receiver. Though capable of correcting for post-cursor ISI, conventional DFE cannot correct for pre-cursor ISI in a received analog data signal. Accordingly, a receiver may include a linear equalizer (e.g., by a continuous-time linear equalizer (CTLE)) to correct for pre-cursor ISI in a received analog data signal. Unfortunately, conventional linear equalizers cannot precisely correct for pre-cursor ISI and amplify noise/cross talk in the received analog data signal. Yet another solution to correcting pre-cursor ISI at a receiver can include equalization at a transmitter, but it usually involves large power consumption at the transmitter. Additionally, a pre-cursor equalization may involve additional overhead, such as a backchannel or accurate setting of presets.